1. Field of the Invention
The present invention relates to a photoreceptor reused by grinding an abraded surface of the photoreceptor, and an electrophotographic image forming apparatus, such as a copying machine, a printer, a facsimile machine, etc. using the reusable photoreceptor.
2. Discussion of the Background
With use of an electrophotographic photoreceptor (hereinafter simply referred to as a photoreceptor), a photosensitive layer of the photoreceptor is abraded by a cleaning blade in contact with the photoreceptor and by developer on a developing roller. In addition, a film of toner, a paper powder of a recording sheet, etc. typically adheres to the surface of the photoreceptor.
When the photosensitive layer of the photoreceptor is abraded by the cleaning blade and the developer on the developing roller, a surface roughness of the photoreceptor increases, resulting in deteriorating cleaning performance. When a film of toner, a paper powder of a recording sheet, etc. adheres to the surface of the photoreceptor, the film absorbs moisture, resulting in deteriorating developing performance.
In order to prevent a failure condition such as the deterioration of cleaning and developing performance, a predetermined useful lifetime is set for the photoreceptor. Although photoreceptors used until the end of their useful lifetimes have in the past simply been disposed, such photoreceptors are also now getting recycled for reuse in view of environmental benefits.
When an image forming apparatus employs an electrophotographic image forming process cartridge in which a photoreceptor, a developing device, a cleaning device, etc. are integrally accommodated in a case for a compact design and an easy maintenance, a proportion of the cost of the photoreceptor is relatively great in the electrophotographic image forming process cartridge. Therefore, also in view of reuse of the electrophotographic image forming process cartridge, providing a reusable photoreceptor is economically beneficial.
With regard to background techniques of reusing a photoreceptor, a method of reusing a photoreceptor by dissolving, cutting, or peeling a photosensitive layer of the photoreceptor has been proposed. The photosensitive layer is formed on a substrate of the photoreceptor. Further, another method of reusing a photoreceptor by grinding a surface of a photoreceptor has been proposed.
In the background technique of reusing a photoreceptor by dissolving, cutting, or peeling a photosensitive layer of the photoreceptor, it is necessary to re-form the photosensitive layer. In view of a recycled photoreceptor, the costs of collecting the photoreceptor and removing the photosensitive layer of the photoreceptor are added, resulting in increasing manufacturing costs.
In the another background technique of reusing a photoreceptor by grinding a surface of a photoreceptor, leakage from a device, such as a charging device, a transfer device, and a developing device to which a bias voltage is applied, to the photoreceptor typically occurs depending on a thickness of a remaining portion of the photosensitive layer after having been ground. The leakage to the photoreceptor results in deterioration of image quality.
The conditions of using photoreceptors vary depending on an image forming apparatus in which the photoreceptor is provided, and depending on users. Therefore, a condition of the photoreceptor when the photoreceptor is collected after judgement of an end of its useful lifetime varies. As a result, a condition for reuse of a photoreceptor and a method of reusing the photoreceptor depend on the condition of the photoreceptor when the photoreceptor is collected.
According to one aspect of the present invention, a novel photoreceptor for an image forming apparatus including a charging device that charges a surface of the photoreceptor, includes a photosensitive layer and a substrate on which the photosensitive layer is formed, wherein assuming that xe2x80x9cAxe2x80x9d is a thickness of a surface portion of the photosensitive layer abraded by image forming operations of the image forming apparatus, xe2x80x9cBxe2x80x9d is a thickness of a portion of the photosensitive layer ground by an operation of grinding the abraded surface of the photosensitive layer, xe2x80x9cnxe2x80x9d is a number of times the operation of grinding the abraded surface of the photosensitive layer has been executed, xe2x80x9cCxe2x80x9d is an original photosensitive layer thickness of the photoreceptor, and xe2x80x9cDxe2x80x9d is a thickness of a remaining portion of the photosensitive layer after having been ground by the operation of grinding the abraded surface of the photosensitive layer which is obtained by the equation:
D=Cxe2x88x92[(A+B)xc3x97n+A], 
a relationship between the thickness xe2x80x9cAxe2x80x9d, the thickness xe2x80x9cBxe2x80x9d, the number of times xe2x80x9cnxe2x80x9d, and the original photosensitive layer thickness xe2x80x9cCxe2x80x9d is set such that the thickness xe2x80x9cDxe2x80x9d is equal to or greater than a thickness of the photosensitive layer in which leakage from the charging device to the photoreceptor does not occur, so that the photoreceptor may be reused.
According to another aspect of the present invention, a novel method of reusing a photoreceptor for an image forming apparatus including a charging device that charges a surface of the photoreceptor, includes grinding an abraded surface of a photosensitive layer of the photoreceptor, obtaining a thickness of a remaining portion of the photosensitive layer after having been grounded by the operation of grinding the abraded surface of the photosensitive layer by the equation:
D=Cxe2x88x92[(A+B)xc3x97n+A], 
where xe2x80x9cAxe2x80x9d is a thickness of a surface portion of the photosensitive layer abraded by image forming operations of the image forming apparatus, xe2x80x9cBxe2x80x9d is a thickness of a portion of the photosensitive layer ground by an operation of grinding the abraded surface of the photosensitive layer, xe2x80x9cnxe2x80x9d is a number of times the operation of grinding the abraded surface of the photosensitive layer has been executed, xe2x80x9cCxe2x80x9d is an original photosensitive layer thickness of the photoreceptor, and xe2x80x9cDxe2x80x9d is a thickness of a remaining portion of the photosensitive layer after having been ground by the operation of grinding the abraded surface of the photosensitive layer, and setting a relationship between the thickness xe2x80x9cAxe2x80x9d, the thickness xe2x80x9cBxe2x80x9d, the number of times xe2x80x9cnxe2x80x9d, and the original photosensitive layer thickness xe2x80x9cCxe2x80x9d such that the thickness xe2x80x9cDxe2x80x9d is equal to or greater than a thickness of the photosensitive layer in which leakage from the charging device to the photoreceptor does not occur.
Objects, features, and advantages of the present invention will become apparent from the following detailed description when read in conjunction with the accompanying drawings.